The SWISCO Series 880 Hybrid Balance is a custom pre-tensioned balance manufactured by Caldwell and branded "Ultra-Lift." It is an engineered solution designed to work in both tilt and non-tilt window applications with multiple sash balance components.
The Series 880 Balance has a precisely calibrated spring that lifts 70% of the sash's weight, proving low friction with high lift assistance during operation. With an AMAA Class 5 Rating, they make heavy sashes easy to open and close. The strength rating you need should be printed as a stamp on the tube and will be necessary for identification.
A #8 installation screw will be used to mount the balance to the outside frame.
Make sure not to overtighten the screw during installation!